Implemented != expression

src/main/antlr4/de/hsrm/compiler/Klang/Klang.g4

@@ -56,6 +56,7 @@ expression
   | OPAR lhs=expression DIV rhs=expression CPAR #divisionExpression
   | OPAR lhs=expression MOD rhs=expression CPAR #moduloExpression
   | OPAR lhs=expression EQEQ rhs=expression CPAR #equalityExpression
+  | OPAR lhs=expression NEQ rhs=expression CPAR #NotEqualityExpression
   | OPAR lhs=expression LT rhs=expression CPAR #lessThanExpression
   | OPAR lhs=expression GT rhs=expression CPAR #greaterThanExpression
   | OPAR lhs=expression LTE rhs=expression CPAR #lessThanOrEqualToExpression
@@ -93,6 +94,7 @@ CPAR: ')';
 COMMA: ',';
 EQUAL: '=';
 EQEQ: '==';
+NEQ: '!=';
 LT: '<';
 GT: '>';
 LTE: '<=';

src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java

@@ -102,6 +102,11 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
     return new EqualityExpression((Expression) this.visit(ctx.lhs), (Expression) this.visit(ctx.rhs));
   }
 
+  @Override 
+  public Node visitNotEqualityExpression(KlangParser.NotEqualityExpressionContext ctx) { 
+    return new NotEqualityExpression((Expression) this.visit(ctx.lhs), (Expression) this.visit(ctx.rhs));
+  }
+
   @Override 
   public Node visitLessThanExpression(KlangParser.LessThanExpressionContext ctx) { 
     return new LTExpression((Expression) this.visit(ctx.lhs), (Expression) this.visit(ctx.rhs));

src/main/java/de/hsrm/compiler/Klang/nodes/expressions/NotEqualityExpression.java

@@ -0,0 +1,14 @@
+package de.hsrm.compiler.Klang.nodes.expressions;
+
+import de.hsrm.compiler.Klang.visitors.Visitor;
+
+public class NotEqualityExpression extends BinaryExpression {
+    public NotEqualityExpression(Expression lhs, Expression rhs) {
+        super(lhs, rhs);
+    }
+
+    @Override
+    public <R> R welcome(Visitor<R> v) {
+        return v.visit(this);
+    }
+}

src/main/java/de/hsrm/compiler/Klang/visitors/EvalVisitor.java

@@ -30,6 +30,16 @@ public class EvalVisitor implements Visitor<Value> {
     return new Value(0);
   }
 
+  @Override
+  public Value visit(NotEqualityExpression e) {
+    Value lhs = e.lhs.welcome(this);
+    Value rhs = e.rhs.welcome(this);
+    if (lhs.asInteger() != rhs.asInteger()) {
+      return new Value(1);
+    }
+    return new Value(0);
+  }
+
   @Override
   public Value visit(GTExpression e) {
     Value lhs = e.lhs.welcome(this);

src/main/java/de/hsrm/compiler/Klang/visitors/GenASM.java

@@ -95,6 +95,27 @@ public class GenASM implements Visitor<Void> {
     return null;
   }
 
+  @Override
+  public Void visit(NotEqualityExpression e) {
+    int lblTrue = ++lCount;
+    int lblEnd = ++lCount;
+
+    e.lhs.welcome(this);
+    this.ex.write("    pushq %rax\n");
+    e.rhs.welcome(this);
+    this.ex.write("    popq %rbx\n");
+    this.ex.write("    cmp %rax, %rbx\n");
+    this.ex.write("    jne .L" + lblTrue + "\n");
+    // false
+    this.ex.write("    movq $0, %rax\n");
+    this.ex.write("    jmp .L" + lblEnd + "\n");
+    this.ex.write(".L" + lblTrue + ":\n");
+    // true
+    this.ex.write("   movq $1, %rax\n");
+    this.ex.write(".L" + lblEnd + ":\n");
+    return null;
+  }
+
   @Override
   public Void visit(GTExpression e) {
     int lblTrue = ++lCount;

src/main/java/de/hsrm/compiler/Klang/visitors/GetVars.java

@@ -31,6 +31,13 @@ class GetVars implements Visitor<Void> {
     return null;
   }
 
+  @Override
+  public Void visit(NotEqualityExpression e) {
+    e.lhs.welcome(this);
+    e.rhs.welcome(this);
+    return null;
+  }
+
   @Override
   public Void visit(GTExpression e) {
     e.lhs.welcome(this);

src/main/java/de/hsrm/compiler/Klang/visitors/PrettyPrintVisitor.java

@@ -80,6 +80,16 @@ public class PrettyPrintVisitor implements Visitor<Void> {
       ex.write(")");
       return null;
     }
+
+    @Override
+    public Void visit(NotEqualityExpression e) {
+      ex.write("(");
+      e.lhs.welcome(this);
+      ex.write(" != ");
+      e.rhs.welcome(this);
+      ex.write(")");
+      return null;
+    }
   
     @Override
     public Void visit(GTExpression e) {

src/main/java/de/hsrm/compiler/Klang/visitors/Visitor.java

@@ -11,6 +11,7 @@ public interface Visitor<R> {
     R visit(Variable e);
     R visit(AdditionExpression e);
     R visit(EqualityExpression e);
+    R visit(NotEqualityExpression e);
     R visit(GTExpression e);
     R visit(GTEExpression e);
     R visit(LTExpression e);